Extracting and Comparing Data from 10 Sleep Tracking Devices and Apps

An anonymous reader writes: A Brown University team extracts the previously irretrievable sleep tracking data from the Hello Sense, from the Microsoft Band, and other popular devices by decompiling the apps and using man-in-the-middle attacks. Using this data, they compare their detection of sleep/wake and sleep stages on 10 devices and apps for someone wearing them simultaneously over 9 days to see how they match up. There are some correlations with sleep/wake detection, but sleep stage seems more spurious.